380 



PLANT MORPHOLOGY 



Fig. 325. Early development of the microsporangium of lochroma lanceolatum, X400. 

 Each stage also shows outline of entire anther, X32. A, cross section of portion of young 

 anther with hypodermal initial cells (shaded) ; B, division of initials to form primary 

 parietal cells (outer shaded layer) and primary sporogenous cells; C, later stage, showing 

 two layers of parietal and of sporogenous cells (latter heavily shaded) and differentiation 

 of inner portion of tapetum (lightly shaded) ; D, later stage, showing anther wall composed 

 of epidermis, endothecium, and middle layers; also sporogenous tissue (heavily shaded) 

 surrounded by tapetum (lightly shaded). 



most members of the Compositae, but ordinarily a plate including several 

 or many hypodermal cells appears (Fig. 325A). 



In the development of a microsporangium, the formation of a periclinal 

 wall in each initial separates the outer primary parietal cells from the inner 

 primary sporogenous cells (Fig. 325B). The former, lying immediately 



